Radio ringing system



Jan. 26 1926.,

o; H.- LOYNES RADIO nmeme. SYSTEM Filed August 22, 1925 IINVENTORfilly/ms fwc A TTORNE Y Patented Jan. 26, 1926.

UNITED STATES 1,570,755] PATENT OFFICE.

OWEN H. LOYNES, OF BROOKLYN, NEW YORK, ASSIGNOR TO AMERICAN TELEPHONEAND TELEGRAPH COMPANY, A CORPORATION OF NEW YORK.

RADIO RINGING SYSTEM.

Application filed August 22, 1923. Serial No. 658,776.

To all whom z't may concern:

Be it known that I, OWEN H. LoYNns, re siding at Brooklyn, in the countyof Kings and State of New York, have invented cer tain Improvements inRadio Ringing Systems, of which the following is a specification.

This invention relates to radio transmission and more particularly tocalling arrangements for a radio telephone system.

It is one of the objects of the present invention to provide a callingarrangement for a radio telephone system which shall be simple andeconomical and at the same time dependable in its operation. 'Thisobject, as well as other objects of the invention, is attained byproviding means whereby in re sponse to pulses of ringing current, thegrid potential of the oscillator supplying the car rier current isperiodically changed to transmit a pulsatingly interrupted carrier. Atthe receiving station the pulses are detected and operate a vibratingrelay which supplies alternating current to a relay continuouslyoperated while a ringing signal is maintained, said relay applying aringing frequency in the transmission line.

The invention may now be understood from the following description whenread in connection with the accompanying drawing, the figure of whichshows a'circuit diagram illustrating one embodiment of the invent-ion. I

Referring to the drawing, L designates a transmission line, such as atelephone line, which terminates ata radio station in a hybrid coil 10and isbalanced by means of an artificial line N, so that a transmittingradio channel TL and a receiving radio channel RL maybe renderedsubstantially conjugate. The radio transmitting channel TL includes avacuum tube modulator M and a high power vacuum tube oscillator O. Thelatter tube has its output and input circuits connected together throughwindings 11 and 12 in a well-known manner and is coupled to thetransmitting antenna AT through a winding 13. The output circuit of the0scillator'O is also connected to the output circuit of the modulator Mthrough a choke coil 14, so that the modulationis of the wellknownconstant current type.

The receiving portion of the system comprises a receiving antenna RT,which is connected to suitable tuned circuits and radio frequencyamplifying apparatus schematically indicated at HFA. On the output sideof the amplifier a detecting tube D is provided for the purposeofdetecting the signaling currents modulated upon the radio frequencytransmitted from the distantstation. Low frequency amplifying apparatusLEA is also schematically indicated for the purpose of amplifying thedetected voice frequencies anda low pass filter F is interposed betweenthe detector A and the amplifier LFA for restricting the currents'to beamplified to the voice frequency currents.

The ringing apparatus comprises a high impedance circuit 15 bridgedacross the telephone line L, said bridge being tuned to the ringingfrequency, which may be, for example, 20 cycles per second. A vibratingpolar relay 16 is included in this bridge and in response to receivedringing current vibrates its armature to intermittently open and closethe circuit of the quick acting relay 17. The latter relay is arrangedto increase the negative potential upon the grid of the oscillator sothat the oscillations which are normally transmitted by the oscillator'0 will be interrupted each time the relay 17 is energized. This resultsin the transmission of a radio carrier frequency which is interrupted atthe ringing frequency.

The receiving portion of the calling apparatus comprises a circuit, 18bridged across the output of the detector D, this circuit being coupledto a circuit 19 which is tuned to the ringing frequency and whichincludes a vibrating polar relay 20, the armature of which vibrates atthe detected ringing frequency. The armature I of the polar relay 20,upon vibrating, alternately connects the winding of an alternatingcurrent relay 21 to the positive and negative. pole of a battery sothat, in effect, an alternating current -of ringing frequency is causedto flow through the winding of the relay 21 in response to the ringingsignal. The relay 21, upon being operated, closes a circuitof a relay 22for applying a 20-cycle ringing source to the line L and also closes acircuit of relay 23,'which disconnects the line L from the transmittingchannel TL to prevent the ringing current from being transmitted to themodulator.

' -The operation is as follows: ringing currents incoming from'the lineL cause the polar vibrating relay 16 to vibrate at the ringing frequencyof 20 cycles per second, thereby intermittently energizing the quickacting relay 17. The latter relay each time it is energized attracts itsarmature and connects a supplemental C battery 24 in series with thenormal C battery 25, thereby increasing the negative potential upon thegrid of the power oscillator so as to interrupt the normally transmittedcarrier frequency generated by the oscillator. At the distant receivingradio station apparatus will be provided similar to that shown in thediagram and the interrupted carrier will produce a ringing signal in amanner similar to that which will now be described in connection withthe receiving apparatus of the diagram illustrated.

Assuming that a radio frequency transmitted from the distant station andinter rupted at the frequency of the ringing current is received by thereceiving antenna RT, the apparatus HFA amplifies the received currentand impresses it on the detector D. Pulses are thus produced in theoutput circuit of the detector D, the frequency of the pulsescorresponding to the ringing frequency. These pulses flow into thecircuit 18 and operate the vibrating polar relay 20 which is in thetuned circuit 1.9. The relay 20 thereupon causes its armature to vibrateat the frequency of the ringing signal and alernately connects positiveand negative potentials to the winding of the relay 21. An alternatingcurrent of ringing frequency is thus, in effect, caused to flow throughthe winding of the relay 21. This relay, being of the alternatingcurrent type, is continuously energized during the interval that theringing current persists and, upon attracting its armature, closes thecircuits of the relays 22 and 23.

Belay 22 disconnects the circuit 15 from the polar relay 16 and appliesa ringing source to the circuit 15 so that ringing current istransmitted to the telephone line L. At the same time, the relay 28disconnects the line L from the hybrid coil 10 to prevent a false signalbeing transmitted to the modulator.

'It will be obvious that the general principles herein disclosed may beembodied in many other organizations widely different from thoseillustrated without departing from the spirit of the invention asdefined in the following claims.

hat is claimed is:

1. In a radio system, a vacuum tube oscillator for supplying radiooscillations, means to apply voice currents to said oscillator to causesaid oscillator to modulate the generated radio oscillations inaccordance with said voice currents, means responsive to ringing currentfor intermittently changing the grid potential of the oscillator tointermittently interrupt the generated radio frequency, and means at areceiving stat on responsive to the interrupted radio fre quency forproducing a ringing signal.

2. In a radio system, a vacuum tube oscillater for supplying radiooscillations, means to apply voice currents to said oscillator to causesaid oscillator to modulate the generated radio oscillations inaccordance with said voice currents, means responsive to ringing currentfor intermittently changing the grid potential of the oscillator tointermittently interrupt the generated radio frequency, a detector at areceiving station for detecting a ringing frequency current from theinterrupted radio frequency, and means responsive to the detectedcurrent for transmitting a ringing frequency current.

3. In a radio system, a transmitting channel and a receiving channel, atransmission line associated with said channels, a vacuum tubeoscillator in the transmitting channel for supplying a radio carrierfrequency, means to apply voice currents to said oscillator to causesaid oscillator to modulate the generated radio oscillations inaccordance withsaid voice currents, means responsive to ringing currentstransmitted over said signaling line for intermittently changing thegrid potential of said oscillator tube so that a radio frequency will betransmitted which is interrupted at the ringing frequency, a detector insaid receiving channel for detecting signaling currents from receivedradio frequency currents, and means associated with said detector fortransmitting ringing current to said line in response to a detectedringing current.

4t. In a radio system, a transmitting channel and a receiving channel, atransmission line associated with said channels, a vacuum tubeoscillator in the transmitting channel for supplying a radio carrierfrequency, means responsive to ringing currents transmitted over saidsignaling line for intermittently changing the grid potential of saidoscillator tube so that a radio frequency will be transmitted which isinterrupted at the ringing frequency, a detector in said receivingchannel for detecting signaling cur rents from received radio frequencycurrents, a vibrating polar relay associated with said detector tuned tovibrate at the ringing frequency, an alternating current relay adaptedto be energized by alternating cur rent applied to its winding inresponse to the operation of said vibrating polar relay, and a source ofringing current arranged to be connected with said telephone line inresponse to theoperation of the alternating current relay.

5. In a radio system, a transmitting channel and a receiving channel, alow frequency signaling line associated with said channels, means inconnection with said transmitting channel for radiating a radiofrequency interrupted at a ringing frequency in response current to saidrelay in response to vibra- 1 to ringing currents from said lowfrequency tions of the armature of said polar relay, signaling line, adetector associated With said alternating relay operating to connectsaid receiving channel, a vibrating polar a ringing source to saidtelephone line in relay in the output circuit of said detector, responseto a detected ringing current.

said polar relay being tuned to vibrate its In testimony whereof, I havesigned my 15 armature at the frequency of ringing pulses name to thisspecification this 20th day of detected by said detector, an alternatingcur- August, 1923.

rentrelay, means to supply an alternating OWEN H. LOYNES.

